168 Mr Nasmyth on the Human Mouth, 



better able to appreciate the peculiar mechanism displayed 

 in its contrivance. 



Let us first inquire what are the different duties demand- 

 ed of these parts, and then point out the mode in which 

 the performance is provided for. 1. There are certain 

 duties exacted of all mankind from the mouth, namely, seiz- 

 ing, dividing, and grinding the food. For each of these ac- 

 tions there exists a central point of energy. The central point 

 of energy for the act of seizing, resides in the median divi* 

 sion, where the canine tooth is situated. That tooth has the 

 most powerful single fang of any tooth in the whole dental 

 range ; and from its strongly pointed cusp, it is peculiarly 

 fited for the act of transfixion. The canines are most con- 

 spicuously marked in many of the lower animals, and known 

 by the name of tusks. They are also powerfully marked in 

 carnivorous animals, such as the dog, from which, indeed, 

 they have obtained their appellation ; but they are not less 

 so amongst the feline and other carnivora. The canine 

 tooth presents a marked feature in the countenance of all 

 animals possessing it. Its position is beautifully adapted for 

 seizing securely, without interfering with the vision of the 

 animal, whilst he is grappling with his prey ; it being placed 

 aside, and not in the direct line of vision. This is a matter 

 of great importance when these teeth require to be brought 

 energetically into action as the duties exacted of them are 

 of primary importance, and must precede those of the others. 

 On each side of this latero-median and essential tooth, are 

 teeth which are of an intermediate character. The lateral 

 incisor teeth, anterior to the canine, partake of a mixed 

 character of the canine and centre incisor, and the small 

 grinders or bicuspides, on the other side, are intermediate in 

 character between the canine and the true molar or grinders ; 

 thus the canine at each corner pierce and transfix whatever 

 is placed within their sphere of action, and hold it fast, 

 while the anterior and intermediate accessories, the lateral 

 incisors, divide it anteriorly, and the acute and compound 

 cuspidated small grinders divide it posteriorly. The other 

 two divisions of the dental range contain within each re- 

 spectively a central sphere of energy also, but very different 



